DE2243016C3 - Process for the production of acrylonitrile from propylene - Google Patents

Description

example 1

The catalyst was prepared according to Belgian patent specification 6 22 025 as follows:

! 25Og Eisennitrai (Fc (NOj -9H _3, (J) were melted at 70 ⁰ C. 455 g of Sb ₂ O ₃ were gradually added under stirring. The whole was "etrocknet and calcined up to 250'C. The obtained Powder was mixed with 20 weight percent ammonium bicarbonate and 5 weight percent stearin The mass was moistened with 3% water and extruded to give small cylinders 3 mm in diameter and 4 to 5 mm in length.

The catalyst was activated then proceed according to the following encryption ^'5: It was heated in a muffle furnace for 4 hours at 100 ° C; then the temperature was 12 m Su jn to 300C, AAnn in 4 hours to 650 ⁰ C and finally raised in an hour to 800 C. The temperature was held at this value for 2 hours.

The ammonium oxide ion was carried out under the conditions shown in Table 1.

In the case of the microreactor, the reaction products soluble at room temperature and ammonia were _{absorbed by blowing into a 1/2 η solution of H 2} SO ₄ and the recycling gas, which consisted of nitrogen and smaller amounts of oxygen, carbon dioxide, propylene and carbon monoxide was recovered in a Mariotte flask, through which it was then returned to the reactor in the desired amount.

In the case of the 1 m long reactor with a diameter of 2.54 cm, the gases that came out of the reactor were passed through a spacious vessel containing water _{after absorption in 1/2 nH 2} SO _{4, in which the in} Water condensable gases condensed, and partially recycled by a diaphragm pump.

In all cases the gaseous mixtures entering or leaving the reactor as well as the recycled gases were analyzed by chromatography. The results listed in Table 1 show that when working according to the invention, the selectivity for acrylonitrile and the conversion are improved.

example

The catalyst was prepared according to Belgian patents 6 22 025 and 8 59 097 as follows:

900 g of a solution containing 45% by weight of iron nitrite were heated to 80 ° C .; 322g · Sb ₂ O ₃ were added gradually to this solution while the temperature was maintained at about ⁰ C KX).

Separately, 4.7 ρ ammonium tungstate (5 (NH _{4 I 2} -0.12 W 0.5 H ₂ O) and 7 a telluric acid (H ₂ TeO ₄ ) in 100 cm ^{5 of} water and 50 cm ³ one per 100 cm - ^{Dissolved 1} 36 g solution containing hydrogen peroxide.

This solution was added to the suspension prepared above, and the whole was heated by heating dried up to 250C with continuous stirring. 10 weight percent urea were with the powdered mass mixed, the moistened and into narrow cylinders of 5 mm length with a Diameter of 3 mm was extruded.

The other operations were on the catalyst carried out as in Example 1. The reaction was carried out according to the procedure described in Example 1 carried out, whereby the conditions listed in Table 2 were observed.

The results shown in Table 2 also show that the selectivity for acrylonitrile is noticeably higher is when working with a recycled material of the non-condensable reaction products.

example

The catalyst was prepared as in Example 1.

The ammonoxidation was carried out in accordance with the procedure described in Example 1 and carried out under the conditions listed in Table 3.

Essentially all of the gases were recycled during the 50 hour run of the two tests siert, but their amount to avoid a considerable increase in the recycling gases

Table 1

End of the test was _{kept constant by adsorbing the CO 2} obtained from the reaction with lime and removing certain amounts of the recycle gas at intervals.

The recycle gas for the second test was initially nitrogen, gradually mixed with propylene. Oxygen and CO ₂ contained in the gases exiting the reactor became enriched.

Space flow rate of C ₃ H ₆ (cm ³ per cm ^{3 of} the catalyst per hour)

Molar loading ratios
NH ₃ to C ₃ H
Air to C ₃ H ₀
Water to C _x H _n
Recirculated gas to C ₁ H ,,

Microcactor

50 50

Reactor (1 ni long, 2.54 cm diameter)

30th

1.2: 1 1.2: 1 1.2: 1 1.2: 12.5: 1 12.5: 1 15: I. 15: 10: I. 0 30: I. 0 0 10: 1 0 30:

continuation

Microrcaklor

Reactor 11 m long. 2.54 cm diameter)

Conversion temperature ("C)

Total conversion of C ₃ H ₆ Selectivity for acrylonitrile Acrylonitrile yield (%)

Table 2

472

460

462

89.6 94 64.2 83 71.7 78.2 68.9 763 64.3 73.6 44.2 63.2

Microreactor

Space flow rate of C ₃ H ₆ (cm ³ per cm ^{3 of} the catalyst per hour)

Molar feed ratios NH ₃ to C ₃ H _6, air to C ₃ H, water to C ₃ H ₆ recycled

Gas to C ₃ H ₆ conversion ^{temperature (0} C)

Total conversion of C ₃ H ₆ selectivity for acrylonitrile (%) acrylonitrile yield (%)

Table 3

Space flow rate of C ₃ H ₆ (cm ³ per cm ^{3 of} the catalyst per hour)

Molar feed ratios NH ₃ to C ₃ H ₆ oxygen to C ₃ H ₆ water to C ₃ H ₆

Recirculated gas to C ₃ H ₆ conversion ^{temperature (0} C)

Total conversion of C ₃ H ₆ selectivity for acrylonitrile (%) acrylonitrile yield (%) reactor (I m long.
2.54 cm diameter)

50

30th

1.3: 1 1.3: 1 1.3: 1 1.2: 1 1.2: 1 1.2: 1 13.5: 1 13: 1 13.5: 1 15: 1 15: 1 15: 1 15: 1 0 0 20: 1 0 0 0 10: 1 10: 1 0 30 · 1 30: 1 475 476 485 480 477 478 89.8 91.6 95.5 69.5 80 88.6 73.8 88.4 87.6 70.8 87.4 89.4 66.1 81 83.65 49.2 70 79.2 Microreactor

50

50

1.3: 1 1.3: 1 2.5: 1 2.5: 1 20: 1 0 0.3: 1 20.3: 1 475 475 100 100 72.7 82.1 72.7 811

1 sheet of drawings

Claims (1)

Claim: Process for the production of acrylonitrile by converting a starting mixture of propylene, Ammonia and oxygen or gases containing oxygen over an ammoxidation catalyst based on antimony, characterized in that one all or part of one or more of i Leaving the synthesis reactor are in particular carbon dioxide, carbon monoxide, nitrogen, argon and saturated Hydrocarbons with 1 to 4 carbon atoms. The antimony-containing catalysts used in the process of the invention are the known antimony-containing catalysts; they also advantageously contain iron, tin, uranium and cerium. These catalysts can also ee rerer of the leaving the reaction zone, in - ° smaller amounts of other elements contain water, non-condensable gases together such as one or more of the promoters Si ber, Kup with the starting mixture in the reaction zone fer, manganese and nickel or other usual Prointroduces, so that the molar Ratio of inert
Gases to propylene in the range of 3: 1 to 50: 1 Engines. The present invention will now be explained on the basis of the drawings. ^b ' Through 4 propylene 1, ammonia 2, acid substance or oxygen-containing gases 3 and recycled gases 15 in the reactor 5 with a fixed bed catalyst The synthesis of unsaturated nitriles or introduced by sator. The acrylonitrile reaction products are introduced into the acid scrubbing column 7 by reacting olefins or propylene through 6, pylene with ammonia and oxygen or oxygen from which an aqueous solution of (NHI ₂ SO ₄ through 9-containing gases over a catalyst is be The acid scrubbing column operates at known (cf. for example DT-OS 21 04 016, which is such a temperature that organic Pro-DL-PS 59 088 and DT-AS 11 62 830) The vapors are known processes for the synthesis of acrylonitrile, passed at 25 through 10 to the absorption column 11, in which the catalysis based on antimony are washed with water coming from 12, while 13 removes an aqueous solution containing all of the acrylonitrile, acetonitrile, acrolein and HCN produced; this solution is sent for subsequent treatment to recover and purify acrylonitrile. A mixture of C ₃ H ₆ and non-converted O ₂ . CO and CO ·., Which were formed in the reaction, as well as ^ _ _ _a ^ derived inert gases. Part of this mixture is necessary to divert water vapor into the reactor 35 through 16 and in part through 15 in order to avoid overheating. Recycled reactor. The amount of derivative by A process for the production of 16 has now been _{found by the amount of O 2} in stream 3 and by acrylonitrile, which surprisingly overcomes the disadvantages above the amount of CO produced in the reaction and determines the thermal and CO ₂ . The amount of recycle by 15 control with the aid of materials that can easily be recycled 40 is determined by the need to be able to react, simplified. To be diluted with the inventive mixture to avoid overheating of the y y where catalysts based on antimony are used. Examples are the Japanese Patent specification 42 02 64, Belgian patents 5 92 434 and 6 22 025, U.S. patents 3198750 and 33 38 952 and Italian patent 8 59 097. However, these known methods have several disadvantages. So many result in unsatisfactory ones Yields, unconsumed propylene must be separated before reuse, and often i di The results obtained according to the method are of particular interest because they are in addition to the desired results Increase in sales also completely unexpectedly increases the selectivity. The invention therefore relates to a method for producing acrylonitrile by reacting a starting mixture of propylene, ammonia and oxygen or gases containing oxygen over one Avoid catalyst bed and therefore varies with the type of catalyst used, with the type of reactor and with the feed material selected.The molar ratio of inert gases to C ₃ H ₆ is in the range from 3: 1 to 50: 1, preferably from 5 : 1 to 20: 1, with inert gases meaning those that are contained in stream 15 or that are contained in the fed-in C ₃ H ₆ (stream 1) or O ₂ (stream 3) Ammonoxidation catalyst based on 50 are included. Antimony, which is characterized in that it can be used as a diluent for the reaction gases all or part of one or more of any substance may be used under the conditions of the conditions of propylene ammonium oxidation leaving the reaction zone, which are not non-condensable gases together with the acted out, such as N ₂ , CO, CO ₂ , light paraf- feed gas mixture into the conversion zone, so 55 Finnish hydrocarbons, argon, that the molar ratio of inert gases to pro- The following examples illustrate the invention, pylene ranges from 3: 1 to 50: 1. The yield is the product of propylene The gases which are not condensable in water and which denote the conversion and selectivity for acrylonitrile. The turnover is defined by the following formula: ". .... moles of converted propylene _{tnn Propylene conversion} (%) = - γγτ ϊ _: - ^ f · 100. Moles of propylene fed The selectivity of acrylonitrile is defined by the following formula: Selectivity (%) = Moles of converted propylene 100